The invention relates generally to mechanisms for retracting a plunger, and more particularly to mechanisms for retracting a plunger upon rotation of a handle.
It is often desirable to retract a plunger that extends into another structure in order to move the object from which the plunger extends, or the structure into which the plunger extends. Pivoting and sliding doors and windows commonly use retractable plungers to hold the door or window in place relative to a frame, and then free the door or window for movement once the plunger is retracted. Complex mechanisms are used to retract a plunger along one axis as the result of rotating a handle along another, typically perpendicular axis. Common doorknobs are but one example of such a mechanism. Besides the perpendicular axes, modern doorknobs suffer from the requirement that the user have sufficient ability to grasp the knob while simultaneously rotating. While this is an action that able-bodied humans take for granted, a significant portion of the population suffers from difficulty in such movements. As a result, the L-shaped door handle has become widely used due to its ability to permit entry without the requirement for grasping and rotating. One need merely push the handle near the end farthest from the pivot axis with a small amount of strength or weight, and the plunger is easily retracted. The door is then pushed open.
L-shaped handles retract the plunger along an axis that is perpendicular to the axis of rotation of the handle. This works well in the case of doors and windows, in which the handle is on one side and the plunger extends along the plane of the door into the door jamb or frame. In some situations, however, a plunger must be retracted along the pivot axis of the handle, such as the case in fitness equipment.
Conventional fitness equipment uses weight plates, which are typically cast iron plates, that stack on one another, and through which a bar extends. The top of the bar is connected to a cable or other high-tensile strength flexible material. The opposite end of the cable, after winding through one or more pulleys to direct the cable to a desired location, is attached to a handle for being grasped by the user of the fitness equipment. The location of the handle can often be moved, such as by removing a screw or other fastener, rotating or sliding the handle along a beam or bar, and then inserting and tightening the screw or other fastener into the handle or a collar through which the handle or the attached cable extends. Like conventional doorknobs, however, the use of such fasteners to move components of fitness equipment can be extremely difficult for those without the ability to grasp and rotate.
Therefore, the need exists for a means for fastening that does not require the ability to grasp and rotate.